Currently, anaerobic digestion, aerobic digestion, gasification, product-packaging separation, trans-esterification, drying, and prilling are used as independent processes. Each process requires feedstock as input and is designed to produce one or more marketable products as output. Additionally, each of these processes produces by-products (also called co-products) that may become commercially valuable product and a source of revenue, or an operating expense for disposal, or an environmental liability. Examples of these by-products are digestate (digestion yields), new soil product, new fuel product, bankable carbon to be sequestered, woody oversized particles (composting yield), ash (gasification yields), and glycerin (trans-esterification yields).
Generally, energy output is also considered a by-product. For example, heat production from composting, biogas from digestion, and syngas from gasification are by-products. Accessories fueled by biogas from digestion include hot water heaters, electricity generation, radiant space heaters, lighting, fireplaces or fire pits, barbeques, cooking equipment, and CNG vehicle fueling.
Organic waste processing facilities are typically designed at a scale of 100 to over 1,000 tons per day. They exist in four industrial sectors: wastewater treatment, manure treatment, industrial process plants, and urban organic recycling plants. These processing facilities control feedstock preparation, residence time, temperature, moisture, density, oxygen, pH, and particle size. They may also control odors, typically with a one-stage treatment system.
Commonly, design and deployment of facilities that employ anaerobic digestion, aerobic digestion, gasification, product-packaging separation, trans-esterification, drying, or prilling processes requires between 2 and 4 years from initial project kickoff to actual commissioning. They are also typically designed as large, centralized facilities based upon the presumption that larger facilities are more cost-efficient due to the larger economies of scale. This presumption has proven to be incorrect or erroneous in most urban organic recycling situations due to the high costs of odor control, the high costs of hauling and transportation of feedstocks (as inputs), and the high costs of hauling and transportation of by-products (as outputs) over increasingly longer distances.
In certain circumstances, or geographic areas, the construction of these types of facilities may also face an added set of problems as local conditions may make it extremely problematic sourcing the requisite materials for constructing the facilities, or constructing with poor weather conditions, or constructing with poor-quality geotechnical conditions. In such circumstances, prefabrication of portable systems reduces risk and ensures more reliable performance of facilities that employ anaerobic digestion, aerobic digestion, alternating digestion, gasification, product-packaging separation, trans-esterification, drying, or prilling processes.
There is a desire and need for renewable energy, energy independence, distributed energy generation, diversion of organic waste from disposal, and zero waste systems. (“Zero Waste Movement”). Coupling two or more of the above technologies (modes) together in a synergistic way to reduce by-product waste and increase usable energy/heat production will help achieve the goals of the Zero Waste Movement. For example, trans-esterification can benefit from a downstream anaerobic digester to convert surplus glycerin into valuable energy and fertilizer. The practice of coupling these technologies can be referred to as by-product synergy. The use of machinery that replicates natural systems that are similar to those used by plants or animals is referred to as bio-mimicry. For example, an anaerobic digester replicates a cow's gastrointestinal tract with regard to mastication, multiple stomachs, gas production, and fertilizer production.
There is also a need to install smaller scale digester bio-mimicry systems as stand-alone systems near locations where the waste products are generated to minimize or eliminate trucking waste. By delivering prefabricated smaller scale bio-mimicry systems to the point of use, reliable cost-efficient bio-mimicry systems may be employed by more users in more diverse locales. The combined effect of use of smaller scale multi-modal systems, the elimination of trucking costs, and prefabrication creates the benefit of lower risk, distributed utilities, and more local resiliency regarding jobs, energy, food, and other resources.